Automatic projector



C. E. SLAUGHTER' AUTOMATIC PROJECTOR Filed May 4, 1931 4 Sheets-Sheet lf? 1dr -f IN ENToR.

June 25, 1 935.

June 25, 1935. c. E. sLAUGHTl-:R 2,005,759

AUTOMATIC PROJECTOR I Filed May 4, 1931 4 SheebsbSheet 2 H0 Vans IN V ENTOR.

m. fwrv `une 25, 1935. c. E. SLAUGHTER 2,005,759

AUTOMATIC PROJECTOR Filed May 4, 1931 4 sheetssheet 5 2 4 I y l 14 2'June 25, 1935. Q E; SLAUGHTER y 2,005,759

AUTOMATIC PROJECTOR INVENTOR.

Y Patented June 25; 1935 vUNITED "STAT-Es PATENT ori-"ice 2,005,759 pAU'roMA'rlcPRoJCToR charles E.l slaughter, Montclair, N.J. ApplicationMay 4, 1931, Suerial'Nm 534,819

1 claim. (c1. l32x- 28) This invention relates to an automatic pro.jector adapted to project images from atravelling lm situated in theprojector, such propulsion being secured by electrical means preferablythrough the agency of an electromagnet the current to which is suppliedintermittently through.

a flasher or thermostatic control of a. similar nature or otherautomatic make-and-break device, permitting the projection lamp to-beshut' off intermittently with 'consequent opportunity for cooling, aswill be referred to more fully below. The lm used for the purpose may beof -the .ordinary standard moving picture lm type and thepictu'res',Aphotographs,l emblems or legends thereonmaybe arranged in the positionof the frames of normal moving picture film or they may be placedatright angles thereto, according to Whether such lm is used in a verticalor horiand horizontal types of a projector having diff ferent methods oflm propulsion are illustrated. Figures l1 to 5 inclusive depict anapparatus of magnet directly actuating the ilm; normal jerkiv ness ofthey magnet armature being vrestrained v by an oil bath damper which isan importantv adjunct in the prevention of breakage of film and forother reasons., i

In these drawings Figal isa vertical section along the lineqA-A of Fig.3. v

Fig. 2 is'a vertical section Valong the line'B-:B

of.Fg.'3.

the Vtopovf the enclosing .case or.container. re-

moved.

guide'showing a portion-'cfa film.

ployed inl.,th'e: foregoing. y y

,.ligures; 6 Tto Qinclus'ive-gdepictjan; apparatus 'of thejhorizontalnlm type, Fig. 6 being a. horizontal, Ionsiiuflmal section showingpart-.0f .the arpa-,-

55. ,xratusfin elevati@ Fig.. 8 is aryiewfalong the line of Fig; 6.

hereinafter described. The lm preferably is pass to the mirrorthenthrough lm land reference characters represent like parts, verticalthe vertical lm type equipped with an electro-@ Fig. 3 depicts a planviewof the apparatus with .F1a 51S- awning. diagram which-.mer befmr,

g,.,':1i s a plan vile alongtheline of Fig. A I

'Y contact II8, ,is also, in electrical The ventilated housing Icontains thel vertical or upright support -termedthe chassis 2 ofvasbestos board or other insulating material, upon which is mounted theoperating mechanism.' ,3 is a thermostatic flasher, 4 is a solenoid'type electromagnet, to which the shaft 5 is attached; this shaftcarryinglcompression spring 6. VThe electromagnet device is immersed'ina container lled with a suitable insulating oil as indicated on thedrawings (see particularly Fig.,2). The rocker arm 1, is mounted onbearing 8 and car-V ries pawl 9 which actuates the ratchet wheel I0 onthe energizing of the electromagnet 4. Ratchet wheell I0 is keyed'onshaft II which also carries backstop'wheel I2 and lm sprocket I3. 32 isa -pawl to-prevent backlash. I4 is an endless band of picture lm. I5, I5are two rollers and I6 is an idler roller mounted on swingingarm I1 andarranged to create a suitable tension of the film. On the armature ofthe `magnet 4 is mounted a spring contact I8, and on the body 'of Vthemagnet contact I9, mounted on insulated block 20. 2| is vthe projectionlamp. 22 is the lamp housing. 23 is a. concave 'reecting mirror, 24 a45l angle mirror 'or prism, 25 a'condenser lens, 26 a lm gate and 2'I aprojection lens. An opening is situate in the vertical supportingv wall(chassis 2) to permit the illumination rays to projection lens. y v

The method o f operation is as follows. vWhen the current is turned on,the thermostatic flasher 3 heatsu'p and closes the electric circuit,allowing the current to ow through the coilof the electromagnet 4. Asthe armatureis drawn into thev magnetic field; the shaft 5= which isattached to the armature, and is alsohnged tothe rockerl arm 1, is drawndown; thus compressing-'the spring 6. Since, however, the rocker armv ismounted on the bearing 8 the pawl vil is raised as the armaturemovesdo'wn, and, engaging with the tooth of the'ratchetV wheel i II),causes the ratchet wheel Ill to actuate the lm'sprocket' the,y distanceof one frameg'This ratchet-wheel IIIA andthe lm sprockety I3, it shouldbehoted are 45 both keyed to theyshaftphllvghence the'film'.` sprocketI3 'movesa'predeterminedxldegree 'with each vimpulse landV so 'shifts.theflm I4 one frame.; In otherwords .the movement is adjusted so thatas 'the sulenid 'armature of, the? magnet' the flasher breaks circuitthe current is cut off,

the lamp goes ou and themagnetic field is destroyed. The compressionspring 6 then pushes the shaft 5 and the armature of the magnet to theopen position. The rocker arm 1 moves about bearing 8 lowering the pawl9, and the cycle -is complete'. 'Ihe operation repeats itself as soon asthe fiasher 3 heats up again to form the new contact. During the briefinterval the lamp is extinguished in the cycle, cooling sets in, aneffect which is enhanced by allowing a free fiow of air through thehousing. Cooling is of great importance as will be later explained. Thecooling period when the light is out may last only a few seconds in eachcycle yet this suffices to secure ample cooling action. v

Due to the damping effect of thetii bath, this -method is particularlywell adapted to A. C. current, 'since the oil tends to cut down thealternating current hum that might otherwise be objectionable. Moreover,the damping effect of the oil bath prevents any sudden jerking of thefilm, with consequent likelihood of breakage, as the first surge of thecurrent flows through the magnet. the fact that the flasher contactpoints are only called upon to carry the current of the magnet j in theoriginal closing of the circuit. The Contact tension of the spring 3|.

for the lamp is carried separately by the contacts within the magnethousing.

Figures 6 to 9 (horizontal type of machine) show a modified mechanism.The housing I contains chassis 2. 3 is a thermostatic flasher, 4' is asolenoid type electromagnet, 5' is a shaft bolted to the armature of thesolenoid. 28 is a connecting rod from shaft 5 to rocker arm l', whichcarries pawl 9'. Ratchet wheel IIJ' is mounted on shaft which alsocarries film I4 is an endless band of picture film. l5' are two rollers,and I6 is an idler roller mounted on swinging arm I1 kept under` tensionby spring 3B. 3| is a tension spring, 32 a pawl to prevent backlash, 2|is a lamp, 22 a lamp housing, 25 a condenser lens, 26 a film gate and 21al projection lens.

The method of operation is as follows. When the current is turned on,the thermostatflasher 3 heats up and closes the electric circuitallowing the current to fiow through the coil of the electromagne'tll',l and also through the projecdestroyed. The tension spring 3| isthen able to' act on the racker arm 1,'and the pawl 9 engages with theteeth of the ratchet wheel III causing it to revolve as the armature ofthe magnet returns to the open position. As the ratchet wheel |0 movesround, it also revolves the film sprocket I3', since itis mounted on thesame shaft |I, which in turn moves the lm so that a new frame isbrought' into the gate, ready for projection when the flasher oncemoreheats up and starts the cycle over again.

The sudden jerk, brought about by the current surging through the magnetcoil, is not transmitted to the film, since the actual movement of thefilm is caused by the steady pull of the tenature.

Still another advantage of this method iss'ion spring. There is,moreover, n'o movement of the film while the light is on'.

The use of a thermostatic flasher serves to greatly increase the usefullife of the lamp, since the lamp has the opportunity to cool off everyfew seconds.- Moreover, since the lamp is mounted in a tubular housingwith ample Ventilating holes at top and bottom (see Figs. 6 and 7) aconsiderable draft of air surges up past the lamp not only while it ison but also while it is still hot but not lighted. This quite strongconvection of air avoids the artificial draft which is usually neededwhen the lamp is on continu, ously.

Moving picture llm or analogous film, whether of thenitrocellulose orthe acetate type, is quickly embrittled if maintained above a certaintemper- The maintenanceof the light in full operation would generate somuch heat that cooling below the critical temperature v.of film decaywould be difficult. The present Minvention involving intermittentoperation provides an automatic projector of simple and cheapconstruction in which the development of heat to or above the criticaltemperature of lrii decay may be prevented without the employment ofexpensive and clumsy VentilatingA and cooling accessory apparatus.

It will be evident that by the emp1oyment of matic projector to breakthe current for a length of time adequate to maintain the desired degreeof temperature control, that is, to keep the temperature below thatpoint at which the film disintegrates rapidly. Of [course all film inconstant use in this way is subject to considerable wear and has to bereplenished from time to time but what I seek to avoid by the practiceof the present invention is, as indicated, that undesirable overheatingwhich tends to convert ordinary high viscosity, tough celluloidnitrocellulose into a low viscosity, brittle, fragile form, thus agingthe film rapidly and shortening its life greatly beyond the normalduration. In this manner I am able to' produce an automatic projector4which can be kept in operation continuously (that is with continuousperiodicity)` without any overheating which signifies rapid film decay.

What I claim is In a projecting machine wherein a transparency isintermittently advanced through a step by step movement intermediate aprojecting lens and a source of illumination, apawl and ratchetmechanism for intermittentlyv Aadvancing the transparency, anelectromagnet,v an armature movable by said ele'ctromagnet to.actuatesaid pawl and ratchet mechanism, an electrical cir-- cuit in which theelectromagnet is located, a second electrical circuit connected to saidfirst circuit and in parallel therewith and including said source ofillumination, a normally open switch in said second circuit operable bythe movements of the said armature to close said second circuit,

and a thermostatic flasher in series `with said circuits.

CHARLES E. SLAUGHTER.

